Functional fluids degrade over time through use. The additives in the functional fluids deplete over the lifetime of the fluid in an engine or other mechanical device. Time release additives for engine oil are known. These additives are typically incorporated into thermoplastic polymers which slowly dissolve into the engine oil, see U.S. Pat. No. 4,075,098. Time release additives have also been incorporated into polymers which are oil-permeable at elevated engine temperatures, see U.S. Pat. No. 4,066,559. In another approach, coating oil additives dissolves over time to release additives into the engine oil, see U.S. patent application Ser. No. 2004/0154304A1.
Replenishment of desired additives into the functional fluid will improve the performance of the functional fluid and the device using the functional fluid.
Accordingly, it is desirable to provide controlled release additives for functional fluids which do not require inert carriers or complicated mechanical devices for achieving controlled release metering of the desired additives into the functional fluid.